Platinum and other noble metals can be found in very small quantities as impurities in other metals and their solutions (e.g, copper, nickel, or zinc) in industrial processes. Since these noble metals are very expensive and are needed, for example, in many catalytic processes, recovering even these small quantities would be useful.

Mari Lundström, Aalto University, Finland, and colleagues have developed a method for the selective recovery of platinum from real industrial hydrometallurgical process solutions. These solutions contained large amounts of Ni and very small amounts of Pt, Pd, and Ag. The team used a pyrolyzed carbon (PyC) electrode with a high surface area and recovered the metal using an electrodeposition–redox replacement (EDRR) method. The deposition times and voltages were optimized to provide a selective recovery of platinum over other metals.

The nanoparticles deposited on the electrode surface had an average content of 90 wt% platinum. Other noble metals, such as Pd and Ag, could also be enriched on the electrode surface. According to the researchers, the developed method provides new opportunities for the circular economy of critical metals.

• Platinum Recovery from Industrial Process Solutions by Electrodeposition–Redox Replacement,
  Petteri Halli, Joonas J. Heikkinen, Heini Elomaa, Benjamin P. Wilson, Ville Jokinen, Kirsi Yliniemi, Sami Franssila, Mari Lundström,
  ACS Sustainable Chem. Eng. 2018.
  https://doi.org/10.1021/acssuschemeng.8b03224